This looked like a straightforward mystery from the front cover. I turned it over and the bumph talked about Wilkie Collins and Charles Dickens, a railway accident, and how it affected Dickens, which in turn had effect on Collins.
The narrator is Wilkie Collins. On the whole the book is extremely well developed and is written in such a manner that it encourages the reader to keep turning the pages. (It took me 8 days to read the book, of almost 800 pages.)
There were a couple of things that made it obvious that the narrator was not Wilkie Collins, but Dan Simmons, these were the Americanisms when referring to footpaths and also to certain dates. I did spot one mistake . Wilkie Collins opens up the hole in the coal cellar, that Field and his men had bricked up some months previously. The problem I had with this is Field and his men bricked up a hole in the coal cellar at a different address to where Wilkie re-opened it.
That aside, it's a brilliant book, one which grabs the reader and doesn't let go until it is over.
The narrator does presume that the current day reader would not have read any of his books. I have read only one to date, The Moonstone, and remember being very surprised when I found it had been written in 1868 and not a century later.